The medical device industry produces a wide variety of electronic devices for treating patient medical conditions. Depending upon the medical condition, medical devices can be surgically implanted or connected externally to the patient receiving treatment. Medical professionals or other clinicians use medical devices alone or in combination with drug therapies and surgery to treat patient medical conditions. For some medical conditions, medical devices provide the best, and sometimes the only, therapy to restore an individual to a more healthful condition and a fuller life. Examples of implantable medical devices designed to deliver therapeutic electrical stimulation include neurological stimulators, pacemakers, defibrillators and drug pumps. Most implantable medical devices are powered by an internal battery or other power source associated with or internal to the device.
Because surgery is required to implant most implantable medical devices, it is desirable, particularly in devices that consume power quickly, to make the internal battery rechargeable. An external power source may then be used to recharge the rechargeable battery, commonly transcutaneously via an inductive link between an external coil and an internal coil. Depending on the nature of the implantable medical device and rechargeable battery in question, several hours will commonly be required to fully recharge the rechargeable battery. While some implantable medical devices may be able to deliver therapy to a patient for months or years on a single charge, some devices, particularly those that deliver a relatively large amount of therapy constantly, may consume all of the charge in a battery in a matter of days or weeks.
Commonly, in order to recharge their implantable medical device, patients may sit in close proximity of their external charger, maintaining a recharging head, or the entire external charging device, nearby or within a few inches of their implantable medical device. The rechargeable battery can commonly require several hours to charge from a relatively low amount of charge to a full or nearly-fully level of charge.